Radiotelegraph transmitting system.



0.01003. BADIOTELEGRAPH'TRANSMITTING SYSTEM.

APPLICATION FILED JULY 14. I91].

1 ,278,508. Patented Sept. 10, 1918.

2 SHEETSSHEET l.

fivenior: m C 273}.

RADIOTELEGRAPH TRANSMIITING SYSTEM.

APPLICATION FILED JULY 14. 1911.

1 ,278,508. v Patented Sept. 10,1918.

2 SHEETS-SHEET 2- #Zzvenfar:

I 'so DU III OSCAR C. ROO S, O F ALLSTON, MASSACHUSETTS.

RADIOTELEGRAPI-I TRANSMITTING SYSTEM.

Specification of Letters Patent.

Patented Sept.- 10, 1918.

Application filed July 14, 1917. -Seria1-No. 180,529.

To all whom it may concern:

Be it known that I, OSCAR C. Roos, a citizen of the United States, and a resident of Allston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Improvement in Radiotelegraph Transmitting Systems, of which the following is a specification.

My invention relates to radio-telegraph transmitting systems and more especially to a system in which a key-controlled auxiliary source of electrical energy is employed to render ineffective an arrester that normally prevents the discharge of the oscillating-circuit condenser across the spark gap.

The object of my invention is to provide a transmitting system of this type in which the effect of the auxiliary source of electrical energy is augmented by resonance and interaction between the circuit of said source -and the other parts of thesystem is prevented, and'o'therwise to improve and in.- crease the efliciency of the system.

Three illustrative embodimentsof my invention are shown conventionally in the accompanying drawings; but it will be understood that various modifications may be made'both in the apparatus and the system ofcircuits without departing from the principle of my invention.

In the drawings Figure 1 is a diagram of a radio-telegraph transmitting system involving my invention, and Figs. 2 and 3 are diagrams of modified circuit arrangements.

A transmittingantenna T is associated in any suitable way with the oscillationproducing circuit and is grounded at E.

In each embodiment of my invention a condenser C is connected in series With aninductance L, a spark gap, which as shown may be a. quenched spark gap divided into two parts S, S, and two trigger valves or arresters V, V, one on either side of said spark gap.

I may employ as an arrester a spark gap or a quenched spark gap, or two oppositely arranged rectifiers such as a point and rectifier, a hot and cold electrode rectifier, a mercury vapor rectifier, or an alumior other film arrester, etc. For illustrative purposes only, I have shown two opposed point and plate rectifiers but I do not limit myself to the kind, number or arrangement of the arresters employed, for my object'may be accomplished plate by a variety of devices which will serve normally to prevent the condenser from discharging across the spark gap, which are capable of being rendered ineffective by being broken down by a momentary impulse from an auxiliary source, and which regain their effectiveness immediately upon the cessation of such impulse.

The auxiliary source which I prefer consists as shown of two low-voltage alternating-current generators A, A, of different frequencies serially connected to the Well known rectifying arrangement V which rectiifics both the positive and the negative pulses of the alternating currents impressed thereon. By means of the transformers M, M the energy of the resulting unidirectional impulses is impressed as two alternating currents having twice the frequency of said generators, respectively, upon the circuit which includes the serially connected condenser C and direct-current generator G. Thegenerator G cannot break down a larger gap than S, S and the arresters, therefore, prevent the discharge of the condenser C across the gap unless they are simultaneously broken down. They will be simultaneously broken down 4 (WP-m) times a second where n and m represent the frequencies of the generators A, A, respectively, so that the tone produced in the receiving system Will be the beat frequency of the alternating currents developed as aforesaid in the secondaries of the transformers M, M, and this tone, as will be obvious, maybe widely varied by slightly altering thespeed of one or both generators. My invention will thus be seen to afford a very simple and flexible electrical substitute for various mechanical devices such as the transmitting tone wheel, the rotating spark gap, etc., for securing different tone effects. I

Thereiis an advantage in connecting the generators A, A, in series with each other that is not obtained when,they are in independent circuits as shown in my application Serial No. 180,528, filed simultaneously herewith, and such connection requires the employment of means for protecting the generator G from the effects of the currents developed by said generators.

The advantage of connecting said generators in series is that the maximum beat voltage, which is always the sum of the voltages of the two machines, is much higher for a givenbeat frequency than that which, other things being equal, would be obtained from a single machine developlng current of sald frequency. For example, if the normal or frequency will be 4000 and the total voltage,

will be the sum of the full-speed voltage of one machine plus the half-speed voltage of the other or 300% higher thanthe voltage of either machine running alone at 1000 cycles If, however, the beat frequency is much lower the advantage of the serial connection 0f the generators is more striking. For example, if the frequency of one machine is 8000 and that of the other 7500, the beat frequency will be 500, which corresponds to 1/16 full speed, While the total voltage is 31/32 the full voltage of both machines. Either machine running alone at 500 cycles would generate only 1/16 its normal or full speed voltage or 1/31 the voltage obtained by my arrangement.

The means whereby the generator G is 5 protected from the effects of the generators -A, A, or, generally speaking, interaction between the two systems 1s prevented, consists of a shunt having negligible reactance for the beat frequency connected across the I terminals of saidgenerator. Specifically, as shown in Fig. 1, this shunt consists of the circuit L, C, C, L attuned to the beat frequency of the alternating currents developed in the secondaries of the transformers 85 M, M, said circuit consisting of two serially connected branches, one branch, as C, L,

being attuned to a frequency higher than said beat frequency and the other C, L to a frequency lower than said beat frequency.

The circuit L, C, C, L being attuned to the beat frequency, it follows that said circuit has negligible reactance for currents of said frequency and that the potential drop across the terminals of said circuit is practically nil, so that the generator G is perfectly protected from the auxiliary source.

Choke coils I, I may be used to protect the generator G from the effects of the oscillations developed by the discharge of the condenser C across the gap. Adjustable resistances R, B may be connected in the cir- 4 cuit of the generator G. A conductor X connects 'the junction. of the branches L, C, and L, C, to a point between the ends of the spark gap, so that the arrester V is in shunt with the branch L, C and the arrester V/ in,shunt with the branch L, C, thepoints a, I), being equi-potential points. One branch, as L, C, being attuned to a frequency higher than the beat frequency has a capacity reactance, and the other branch L, C, being attuned to a frequency lower than said beat frequency has an inductance reactance, so that the passage of 85 the beat-frequency current throughthe circuit L, C, C, L, L, C, will develop a high potential difference between the terminals of the arresters V, V, respectively,

breaking them. down sin'iultaneouslyand perage across the arresters for momentarilybreaking them down and rendering them ineffective.

In order to further augment the effect of the auxiliary source by sharper resonance, I-

eliminate the high impedance of the radiofrequency circuit ,C, L for currents of beat frequencies, by using the arrangement shown in Figs. 2 and 3, in which a second circuit L", C, C, L attuned to the beat frequency is connected across the system, said circuit consisting of the branch L', C attuned to a frequency higher than the beat frequency and the branch C, L attuned to a frequency lower than said beat frequency. The branches L-, C and C, L are both attuned to the same frequency and the branches L, C and C, L are both attuned to the same but lower frequency, so that the circuits L C X, C, L and-L, C, X, C, L are each attuned to the beat frequency. The secondaries of the transform-- ers M, M are so connectedthat the beatfrequency currents will flow in the last named circuits, and have a common direction in the conductor X, "thereby avoiding the radio-frequency circuit C, L, which has a high impedance for said current, and being amplified by resonance. In Fig. 2 the arresters will be broken down by the high -potential developed at their respectiveterminals by the currents in the branches L, C, and L", C while there. will be a substantially negligible difference of potential between the ends of the circuits L, C, 'C", L, and L', C, C L thus insuring the safety ofgenerator G. In this case the points a, b, c, are equi-potential points.

The adjustable condenser C" may be connected in the circuit of the primaries of the transformers M, M in order to make said iting the same thereto, what I claim and desire to secure by Leters-Patent is:

1. A radio-telegraph transmitting system, comprising in combination a circuit provided with a condenser and a'spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit forpreventing' the discharge of said current generator, a spark gap connected in shunt to said condenser,'a source of alternating current associated with said circuit, and a circuit having negligible reacta-nce for said alternating current connected in shunt to said direct current generator.

3. A radio-telegraph transmitting system, comprising in combination a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said spark gap, a source of alternating current arranged to act on said arrester, a circuit connected in shunt to said source of electrical energy and attuned to the frequency of said alternating current, the last named circuit consisting of two ria-lly'connected branches, one branch being attuned to a frequency higher than that of said alternating current and the other to a frequency lower than that of said alternating current, and a connection from the junction of said branches to a point between the ends of said spark gap. 7

4. A radio-telegraph transmitting system,

comprising in combination a circuit containing a serially connected condenser and direct current generator, a spark gap connected in shunt to said condenser, a source of alternating current associated with. said circuit, and two circuits each attuned to the fre quency of said alternating current connected across the firstnamed circuit. one on either side of the point of application of said alternating ,current thereto.

5. A radio-telegraph transmitting system,

comprising in combination a circuit containing a serially connected condenser and direct current generator, a spark gap connected in shunt to said condenser, a source of alternating current associated with said circuit, two circuits each attuned to the frequency of said alternating current connected across thefirst named circuit, one on either side of the point of application of said alternating current thereto, each of said circuits consisting of two serially connected circuit for preventing the discharge of said,

condenser across said spark gap, and a circuit containing two serially connected alterating current generators of different fre quencies' associated with said arrester.

7. A. radio-telegraph transmitting system, comprising in combination a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said spark gap, a circuit containing two serially connected alternating current generators of different frequencies associated with said arrester, and a key for controlling the last mentioned circuit.

8. A radio-telegraph transmitting system, conqprisiug in combination a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said gap, two serially connected alternating current generators of'different frequencies, means for rectifying the current delivered by said generators, and

means for impressing the resulting unidirectional impulses upon the clrcuit of said arrester.

9.. A radio-telegraph transmitting system, comprising in combination a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said gap, two serially connected alternating current generators of different frequencies, means for rectifying the current delivered by said generators, and a transformer for impressing the resulting unidirectional impulses upon the circuit of said arrester.

10. A- radio-telegraph transmitting system, comprising in combination .a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said gap, two serially connected alternating current enerators of different frequencies, means For rectifying the current delivered by said generators, and a circuit including an adjustable condenser for impressing the resulting unidirectional impulses upon the circuit of said arrester.

11. A radio-telegraph transmitting system, comprising in combination a circuit provided with a condenser and a spark gap, a source of electrical energy arranged to charge said condenser, an arrester in said circuit for preventing the discharge of said condenser across said gap, two serially connected alternating current generators of different "frequencies, means for rectifying the current delivered by said generators, a circuit-attuned. to four times the frequency of the beats created by the resulting unidirectional impulses,'and means associating the last mentioned circuit with the circuit of said arrcster.

In testimony whereof I ha \0 hereunto subscribed my name thls 2nd day of July, 1917. 20

OSCAR C. ROOS. 

